grammar::is_charset

Alias for std::true_type if T satisfies CharSet.

template<
    class T>
using is_charset = see-below;

This metafunction determines if the type T meets these requirements of CharSet:

An instance of T is invocable with this equivalent function signature:
```
bool T::operator()( char ) const noexcept;
```

Use with enable_if on the return value:

template< class CharSet >
typename std::enable_if< is_charset<T>::value >::type
func( CharSet const& cs );

Type	Description
`T`	the type to check.

Convenience header <boost/url/grammar.hpp>